Battleships open the Second World War as Europe's most feared weapons and end it as escorts for the aircraft carriers that replaced them. The film traces that reversal battle by battle, starting with a German U-boat's night attack on the British battleship Royal Oak at anchor in Scapa Flow, one of the war's first naval shocks. It follows the Battle of the River Plate, then the sinking of the British battlecruiser HMS Hood by the German battleship Bismarck and the manhunt that ends with Bismarck destroyed days later. A turning point comes at Taranto, where British Swordfish biplanes launched from a carrier torpedo the Italian fleet at anchor, proving aircraft could sink battleships without a shot fired back, a lesson the Japanese apply at Pearl Harbor. The second half moves to the Pacific, where American and Japanese battleships fight mainly as gun platforms guarding carriers rather than as the war's main strike force. Archival footage and expert commentary track how air power made the battleship obsolete within a single decade of naval warfare.